Cytology of ductal lavage fluid of the breast.

The cytologic evaluation of nipple aspirate fluids has been shown to identify women at increased risk for developing breast cancer. One limitation of this assay is the often scant cellularity of the specimen. An improved technique, ductal lavage, utilizes a microcatheter inserted into individual breast ducts to collect large numbers of cells for cytologic evaluation. Epithelial cells in ductal lavage fluids can be categorized as benign, malignant, or showing mildly or markedly atypical changes. The cell characteristics which were most helpful in identifying abnormal cells were related to cell arrangement, cell size, nuclear size, and size variation, nuclear membrane irregularity, chromatin granularity, and the presence of large nucleoli. Cell size, nuclear size variation, and large nucleoli were the most robust features, as determined by agreement between two pathologists. Moderate cell enlargement and the presence of large nucleoli were the features selected by structured tree analysis for classifying the specimens into the diagnostic groups. The similarity of the cytology of ductal lavage fluid to nipple aspirate fluid strongly suggests that these specimens will also be useful for predicting breast cancer risk.